Generally, a conventional automatic transmission uses a planetary gear type or countershaft type transmission mechanism and a general transmission method selectively engages clutches that are individually provided on gear positions of different gear ratios.
To solve this problem, Japanese Patent Laid-open No. 2003-113932, for example, has disclosed a transmission apparatus that actively changes gears by combining a motor with a countershaft type transmission mechanism that is equipped with two input shaft. This mechanism can gradually change gears while keeping the driving force of the vehicle during gear changing. Further, it is possible to assist the engine power for acceleration and improve the power performance of the vehicle by adding power from the motor while the vehicle is running normally.